1. Field of the Invention
The present invention relates generally to the area of beds in which upper and lower body sections of a user are independently supported by adjustable articulated bed sections, and more particularly, to a bed in which the bed sections are automatically moved to an approximately coplanar position in response to a single discrete manual actuation of a control device.
2. Description of Related Art
Hospital beds having independently moveable articulated head, knee and foot sections are well known. Typically the articulated bed sections are connected to drive mechanisms independently powered by electric motors. The beds contain pushbuttons or other input devices which may be used to operate the motors in different combinations to achieve a desired configuration of the articulated sections.
U.S. Pat. No. 4,559,655 discloses a hospital bed in which the articulated head and knee sections of the bed are connected to independent drive mechanisms and motors. In the event of an emergency, it is desirable to lower the head section at a rate substantially in excess of that provided by the normal operation of the motor. Therefore, a manually operated control is provided for disengaging the head section from its drive thereby permitting the head section to be moved rapidly downward independent of the drive and motor. The above device positions the upper torso of the patient in the optimum position for immediate treatment in an emergency cardiac situation. However, the device does not control or activate any change of position of the lower torso supported by the knee section of the bed. To change the position of the lower torso, the motor controlling the position of the knee section must be operated by separate manual controls in order to move the articulated thigh and foot sections of the knee section into a position coplanar with the head section. The manual control must be continuously activated by an operator for the full time the articulated thigh and foot sections are moving. Alternatively, the thigh and foot sections may be manually lowered to the desired coplanar position.
U.S. Pat. No. 4,953,243 provides for an automatic hands-free repositioning of a hospital bed to a full-up flat position upon entry of a coded command by an attendant. The coded command is created by the attendant activating a pre-existing hand switch simultaneously with a pre-existing foot control. Preferably, the attendant activates the bed-up foot control and the programmed Trendelenburg hand switch. The bed control has a logic circuit which is responsive to those two commands for simultaneously producing bed-up knee-down and back-down motor command signals. The requirements of a combination of hand and foot commands by the attendant is utilized to prevent the patient from inadvertently inputting the coded command.
The above designs have the disadvantage of either requiring extra manpower or extra time in order to move all of the articulated bed sections to the desired co-planar position. In the first case, the requirement of an independent operation to power drive the thigh and foot sections diverts attention from the immediate emergency treatment being provided. In the other case, hospital bed motors are typically operated at relatively low speeds to prevent discomfort to the patient. Therefore, using the motors to move the bed to the desired co-planar position requires substantial time; and in a CPR emergency, the less time to move the bed, the better.